Some Owls Keep Blind Snakes in Their Nests as Live-in Exterminators

You might hate your apartment, but at least your landlord can’t literally eat you alive. Deep in the heart of Texas, one species of blind snake is living inches below its feathered predator. That can’t be a good idea, right?

Yesterday, Reddit user birdsbirdsbirdsbirds shared a piece of zoological trivia with the Today I Learned community all about—you guessed it—birds.

Birdsbirdsbirdsbirds wrote, “[Today I learned] some owls keep blind snakes in their nests as helpful associates, reducing the abundance of nest parasites.”

Although it was news to birdsbirdsbirdsbirds, scientists actually discovered this curious interspecies friendship about 40 years ago.

In 1975, two biologists from Baylor University found that some eastern screech owls endemic to central Texas were sharing their nests with blind snakes—a surprising observation because the snakes should be the owls’ prey.

The Texas blind snake, AKA Rena dulcis. (LA Dawson/CC BY SA 2.5)

In fact, aside from a few random insects, Texas blind snakes were the only living prey the biologists had ever seen in the birds’ nests, making this interspecies cohabitation even more remarkable.

For scale, here is the flying Furby ornithologists call the “eastern screech owl”:

The researchers—F. R. Gehlbach and R. S. Baldridge—formulated their study after watching “four adult screech owls delivering a live blind snake to its nestlings” and seeing that “all snakes were found alive in the nests the next day.”

By contrast, this is the normal level of hospitality these owls show their serpentine guests:

“Like most raptorial birds, eastern screech owls kill and usually decapitate vertebrate prey before bringing it to the nests. Reptilian prey often dangles from the bill of adult screech owls upon delivery to a nest …”

Of course, the owls still hauled the Texas blind snakes through the air to move them to the nests, but their delivery method seemed gentler. Gehlbach and Baldridge observed that the snakes “were coiled about the bills of the owls that carried them.”

If you’re not impressed by the possibility of owls showing self-restraint with snakes, just imagine the dogs from Lady and the Tramp visiting Tony’s Italian restaurant, ordering a plate of spaghetti, wrapping the noodles around their snouts, walking across town (still holding that same spaghetti), dropping the spaghetti off in the bed of their newborn puppies, and having none of the dogs eat any of the spaghetti.

The phenomenon was—as those in the scientific community say—”weird.” So the biologists had to investigate.

Gehlbach and Baldridge studied 77 eastern screech owl nests, 14 of which (approximately 18 percent) harbored blind snakes. Most nests had just one reptilian resident, though one nest housed 15 snakes over the course of the study (at which point you can’t really call it an owl’s nest so much as a bed-and-breakfast for blind snakes).

Eighty-nine percent of the snakes the owls brought back to their nests stayed alive and well. Four of the 35 total snakes weren’t so lucky.

But before you give owls credit for—as those in the scientific community say—”not eating the spaghetti,” Gehlbach notes that all of the snakes were probably intended as food.

As he writes in his book The Eastern Screech Owl, “These snakes are delivered as food but mostly uninjured, so they burrow in nest debris … there is no evidence that stocking live blind snakes in nests is anything more than accidental.”

According to the biologist, the snakes remained uneaten because of their “writhing defensive behavior and smooth cylindrical body, smeared with repellent secretions.”

Even though the owls failed to eat the snakes, the reptiles proved incredibly useful to the birds’ reproductive fitness once they were transported to the nests because the snakes fed on insects that would otherwise steal the owls’ stored foods.

Gehlbach notes in his book that everything from rats to insect carcasses “slowly disappeared under the onslaught of acrobat ants, fly maggots, and other decomposers.” He concludes that the effects “could be severe, if Texas blind snakes did not reduce the numbers of at least some insect competitors …”

The most important creatures the snakes eradicate are soft-bodied insect larvae, which would otherwise antagonize the baby owls as parasites—or as competition for their food.